I'm updating cods for this theme w/ every new OS released for 9981.
***WARNING***
You can get your stock theme by simply going to Options/Device/Application Management and uninstalling "BlackBerry Porsche Desing P9981 Theme 9900 / 9930" BUT I always recommend installing any other theme and activating it before playing with stock theme. Never had such problem but if anything happens you'll have to reload the OS if you don't have any other theme activated.
the answer is on page 1 of this thread.. if you'd just peeped.
you will need to delete the porsche theme to get the stock theme back.
because this one overwrites the stock theme, so you can't change between them.
and you need to delete it properly, because i have experienced by myself,
yesterday somehow the deleting session went stuck, and my screen went funky.
and therfore i needed to reload my OS.
Cheers, I tried it out, didn't like the theme at all and have reverted back. Nice find though!